Vat colors on nylon



United States PatentQ VAT COLORS N NYLON Henry R. Mautner, Hackensack, N. J., assignor to General Aniline & Film Corporation, a corporation of Delaware No Drawing. Application August 24, 1951, Serial No. 243,579

9 Claims. (or. 8-34) This invention relates to the dyeing of synthetic fibers with vat dyestuffs and more particularly to a method 2 treatment is that it is carried out below 212 F.- and for only comparatively short periods of time whereby the fiber and the color are not adversely affected. Subsequent dyeing operations are carried out in normal manner dependent upon the particular dyestuff employed.

The use of the pretre'ating composition of this invention results in several advantages as compared with the use of phenol per se. Phenol is highly toxic and dangerous to use, producing severe burns on contact with the skin, and hence presents hazards both in application to the nylon and in subsequent use of the treated nylon 1n case the phenol is not completely removed. It has a strong solubilizing and decomposing effect on the nylon of dyeing nylon with vat dyestuffs involving pretreatment of the nylon with a novel composition to increase its affinity for vat dyestuffs and to the products produced by such method.

The application of vat dyestuffs on nylon and other synthetic fibers has been a constant problem with the inunder pressure produces about the same results as dye-' ings at 180-200 F. Various pretreatments with aromatic acids, such as salicylic, cinnamic and tannic acids, increase aflinity of nylon for vat dyes, but these pretreatments have to be carried out at boiling temperatures.

Of these prior treatments the greatest increase in affinity is obtained by boiling the material in tannic acid, i. e., yields are obtained which compare favorably with those on cotton and viscose. Only recently it has been discovered that this pretreatment has an effect which makes it almost useless in light and medium shades. The tannin bottom is not washed out by ordinary means and when dyeings produced by this method are subjected to alkaline washings such as AATCC #3 or 4 the shade changes to such a degree that in. some cases it amounts to destruction of the color. Giving the dyeings an alkaline finishing operation was found to be of -no avail inasmuch as'the beneficial effects with respect to light fastness of the tannin pretreatment were lost.

The object of the present invention is to provide means for minimizing or eliminating the deficiencies of the aforementioned processes. Another object is to provide an improved method of dyeing nylon with vat dyestuffs involving pretreatment of the nylon to increase its atfinity for vat dyestuffs. A further object is to provide a novel composition for use in said pretreatment ofthe nylon prior to vat dyeing. A still further object is to provide a dyed nylon product having a full shade and improved light fastness and other properties. Other objects and advantages will appear as the description proceeds.

The accomplishment of the aforementioned objects is made possible by the instant invention which broadly comprises preliminary treatment of the nylon with a 2 105% solution by weight of phthalic anhydride in a phenol, followed by vat dyeing in known manner.

By the use of this pretreatment, yields are obtained which compare favorably with those obtained in vat dyeing cellulosic material and 'insome cases the yields are "even mcreased The great advantage of the instant preand must therefore be carefully applied under rigidly controlled conditions to avoid damage to the nylon. In

many instances it has a detrimental effect on the dyes subsequently applied, whereby the dyed nylon has impaired properties with respect to light fastness and the like. In contrast thereto the instant pretreating composition has greatly reduced toxic and corrosive properties, producing no ill effects on short contact with the skin. Likewise, it has a reduced corrosive, solubilizing and decomposing effect on nylon and has little effect on the properties of most dyes. Consequently it may be freely applied to the nylon under a greater variety of conditions and in conjunction with the use of a greater variety of dyes.

volved, or the like.

The exact nature of the composition is unknown, as for example, whether'a reaction takes place between the phthalic anhydride and the phenol, whether a complex is formed, whether interfacial phenomena are in- The solution produced by dissolving the phthalic anhydride in the phenol in the required proportions is reasonably stable, but under ordinary atmospheric conditions the anhydride begins to precipitate as the acid after-several days. However, the efiicacy of the solution is not impaired until the concentration of the anhydride in the phenol drops below about 2%, which usually does not occur for at least three months. ile the preferred phenol to be employed is phenol per se, other reasonably wate -soluble phenols may be used, suchas for example cresol and the like.

In putting this invention into practice, the aforementioned composition is dissolved in water in a concentration of aboutl -to 2% per cent by volume. The resulting solution is employed to pretreat the nylon in any suitable manner, as, for example, by immersion, spraying, padding, or the like. This pretreating solution is maintained at about to 210 F. during the treatment and the duration of the pretreatment may range from about 2 to 20 minutes. It will, of course, be understood that, in general, the higher the temperature the shorter the duration of treatment should be and vice versa.

Following the pretreatment, the nylon is rinsed in water and then vat dyed in any suitable manner, as, for example, by continuous dyeing, pad-steaming, pigment padding, jig dyeing (piece work), Beck open vat dyeing, package dyeing, and the like.

The nylon to be treated may be in any form as, for example, staple fiber or continuous filament, slubbing, yarns, warps, fabrics, and the like. The instant invention may be employed in the application of any of the known vat dyestuffs, including dyestuffs of the quinonoid and indigoid type.

The following examples illustrate the invention and are not to be regarded as limitative.

Example 1 A 5.0 g. skein of continuous filament nylon was treated Patented Nov. 9, 1955 of a solution by weight of phthalic anhydride in V were vatted in 200 cc. of water with 1.0 g. NaOH and 1.0 g. NazSzO; for 5 minutes at ISO-140 F. and the wet skein immersed and manipulated in the resulting vat for 35 minutes, then rinsed, oxidized, and scoured. The dyeing obtained was of good yield and shade, and no break after a 40 hour Fadeometer exposure was noted.

Example 2 The foregoing example was repeated except that the dyestufi used was Indanthrene Brown RN double paste (C. 1. 115.1). The results were equally good.

Example 3 A 5.0 g. skein of continuous filament nylon was treated with 5 cc. of a 5% solution by weight of phthalic anhydride in phenol at 200 F. in 200 cc. H2O for 5 minutes and rinsed. The wet skein was thendyed at. l30140 F. in 200 cc. H2O containing 0.2 g. dimethoxyv violanthrone (Schultz No. 1269), Wetted with 1.0 g. NaOH and 1.0 g. NazSzOe. Total dyeing time was 3.5 minutes after which the skein was oxidized and secured. A full shade was obtained which withstood a lOD-hour Fadeometer exposure without break.

Example 4 A 5.0 g. skein of continuous filament nylon was treated with a 5% solution by weight of phthalic anhydride in phenol as in Example 3, and dyed at 130-140" F. with 0.25 g. Indanthrene Dark Blue BO Paste (C. I. No. 1099) vatted with 0.75 g. NaOH and 0.75 g. NazSzOs in 200 cc. H2O. Total dyeing time was35 minutes, after which the skein was oxidized and scoured. A full shade was obtained of the expected hue and excellent levelness.

Example 5 225 g. of nylon staple fiber stock were treated for minutes at 175-180 F. with 3 liters H2O containing 70 cc. of a 5% solution by weight of phthalic anhydride in phenol in a 1 pound laboratory Smith-Drum package dyeing machine and then rinsed. The machine was drained and the valve. from the expansion tank closed preparatory to making up the dyeing liquor. The expansion tank was filled with 2.5 liters of water containing 8.0. g. NaOH and 8.0 g. Na'zSzOs and to this 6.75 g. Indanthrene Golden Orange G double paste. (C. I. 1096), and 2.25 g. of the vat dyestuft employed in Example 1, vatted with 10.0 g. NaOH and 10.0 g. N32S204 at 140 F. The valve was then opened and the dye liquor was pumped into the dyeing chamber whose lid was kept open so as to avoid pressure with a resulting packing of the material. After all the dye liquor was pumped into the dyeing chamber, the valve from the expansion tank was closed and the dye liquor was circulated through the fiber stock for 60 minutes at -l40 F. After this the almost fully exhausted gye dliquor was dropped, the material rinsed and oxitze The resulting dyeing on the fiber exhibited a full shade of the expected hue and of unexcelled levelness, making the material ready for use alone or by blending with other fiber stock.

Example 6 A 5 .0 g. skein, of continuous filament nylon Wastre'ated in 200 cc. of H20 containing 5 cc. of a 5% solution by weight of phthalic anhydride in phenol for 5 minutes at 200 F., rinsed in cold water and dyed as follows:

0.25 g. lndanthrene Brown RN double paste (C. I. 1151) were vatted in 200 cc. H2O with 0.75 g. NaOH and 0.75 g. NazSzO4 for 5 minutes and the wet skein immersed therein and manipulated for 35 minutes at l30l40 F., then rinsed, oxidized and scoured. The dyeing obtained was of good yield and shade and withstood a 60-hour Fadeometer exposure.

Various modifications and variations of this invention will be obvious to a person skilled in the art and such variations and modifications are to be regarded as within the purview of this application and the spirit and scope of the appended claims.

I claim:

1. In a process of dyeing nylon fibrous materials with an alkaline solution of the leuco form of an unesterified vat dye, the improvement comprising pretreating the nylon with an aqueous solution containing '1 to 2% per cent by volume of a 2 to 5% solution by weight of phthalic anhydride in a phenol selected from the. group consisting-of'phenol and lower alkyl substituted monocyclic phenols soluble in water in concentrations of at least about 1 to 2% per cent by volume at the temperature of pretreatment.

2. In a process of dyeing nylon fibrous materials with an alkaline solution of the leuco form of an unesterified vat dye, the improvement comprising pretreating the nylon with an aqueous solution containing 1 to 2% per cent by volume of a 2 to 5% solution by weight of phthalic anhydride in phenol.

3. In a process of dyeing nylon fibrous materials with an alkaline solution of the leuco form of an unesterified vat dye, the improvement comprising pretreating the nylon with an aqueous solution containing 1 to 2% per cent by volume of a 2 to 5% solution by weight of phthalic anhydride in phenol, at a temperature of about 150 to 210 F. for about 20 to 2 minutes.

4. A process for dyeing nylon fibrous materials comprising pretreating the nylon with an aqueous solution containing 1 to 2% per cent by volume of a 2 to 5% solution by weight of phthalic anhydride in a watersoluble phenol selected from the group consisting of phenol and lower alkyl" substituted monocyclic phenols, rinsing and vat dyeing the nylon with an alkaline solution of the leuco form of an unesterified vat dye.

5. A processfor dyeing nylon fibrous materials comprising pretreatirig the nylon with an aqueous solution containing 1 to 2% per cent by volume of a 2 to 5% solution by weight of phthalic anhydride in phenol, rinsing and vat dyeing the nylon with an alkaline solution of the leuco form of an unesterified vat dye.

6. A process for dyeing nylon fibrous materials comprising pretreating the nylon with an aqueous solution containing 1 to 2% per cent by volume of a 2 to 5% solution by weight of phthalic anhydride in phenol, at a temperature of about to 210 F. for about 20 to 2 minutes, rinsing and vat dyeing the nylon with an alkaline solution of the leuco form of an unesterified vat dye.

7. A composition suitable for pretreatment of nylon to increase its affinity for vat dyestuffs comprising a 2 to 5% solution by weight of phthalic anhydride in a phenol selected from the alkyl substituted monocyclic phenols soluble in water in concentrations of at least about 1 to 2% per cent by volume at the temperature of pretreatment.

8. A composition suitable for pretreatment of nylon to increase its afiinity for vat dyestuifs comprising a 2hto 5% solution by weight of phthalic anhydride in p eno 9. An aqueous solution suitable for pretreatment of nylon to increase its afiinity for vat dyestuffs containing 1 to 2% per cent by volume of a 2 to 5% solution by weight of phthalic anhydride in phenol.

References Cited in the file of this patent FOREIGN PATENTS Number Country Date 584,758 Great Britain Jan. 22, 1947 568,092 Great Britain Mar. 19, 1945 645,033 Great Britain Oct; 25, 1950 group consisting of phenol and lower 

5. A PROCESS FOR DYEING NYLON FIBROUS MATERIALS COMPRISING PRETREATING THE NYLON WITH AN AQUEOUS SOLUTION CONTAINING 1 TO 23/4 PER CENT BY VOLUME OF A 2 TO 5% SOLUTION BY WEIGHT OF PHTHALIC ANHYDRIDE IN PHENOL, RINSING AND VAT DYEING THE NYLON WITH AN ALKALINE SOLUTION OF THE LEUCO FORM OF AN UNESTERIFIED VAT DYE. 